The long-term objective of this application is to understand the mechanisms by which carcinoma cells undergo a conversion that allows them to migrate away from the primary tumor. This event constitutes the first stage of the process of metastasis, which remains the major obstacle to reducing cancer-induced mortality. The specific aims of this project are to investigate the roles of fibroblast growth factors (FGF) in the dissociation and in the acquisition of motility and invasive properties of carcinoma cells. The rat bladder carcinoma cell line NBT-II offers a unique opportunity to study this phenomenon as it was recently discovered that acidic FGF can induce specifically and reversibly the conversion from an epithelial to a highly migratory mesenchymal state. The prevalence and affinity of the FGF receptors expressed by NBTII cells will be characterized ; the role of protein synthesis and phosphorylation will be determined in the mechanism of transduction . NBTII cells will be transfected with different cDNA constructs of members of the FGF family. The phenotype of stable NBTII clones will be correlated with the level of expression of cytoplasmic or secreted forms of FGF. Clones of NBTII cells expressing FGF will be further characterized for their morphology , motility, content in desmosomes , cytoplasmic and surface markers of polarity. Cell-cell adhesive properties will be measured quantitatively with a particular focus on cadherins. Transfections will be made with cDNA probes of cadherins which will be modulated during the conversion to the fibroblastic state. The different clones will be tested for their relative ability to invade extracellular matrices and embryonic heart explants in vitro ; they will also be injected in immunosuppressed rat and mice to evaluate their invasive and metastatic potential in vivo. Other cell lines will be tested for their ability to respond to FGF-like growth factors similarly to NBTII; other growth factors will be screened. This project will allow to possibly establish for the first time a clear-cut correlation between invasion and metastasis of carcinoma and cell motility and adhesion properties under the direct or indirect control of acidic FGF and its related oncogene products.